function out=is_octave ()
  %% Determine if we are currently using GNU Octave 
  
  %%       E. Chassande-Mottin
  %%       Copyright (c) 2007
  %%
  %%  This program is free software; you can redistribute it and/or modify
  %%  it under the terms of the GNU General Public License as published by
  %%  the Free Software Foundation; either version 2 of the License, or
  %%  (at your option) any later version.
  %%
  %%  This program is distributed in the hope that it will be useful,
  %%  but WITHOUT ANY WARRANTY; without even the implied warranty of
  %%  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  %%  GNU General Public License for more details.
  %%
  %%  You should have received a copy of the GNU General Public License
  %%  along with this program; if not, write to the Free Software
  %%  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

  persistent inout;

  if isempty(inout),
    inout = exist('OCTAVE_VERSION','builtin') ~= 0;
  end;
  out = inout;
  
  return;


